Modular LED illumination system and method

ABSTRACT

The present invention is directed to an illumination system. The illumination system comprises a plurality of modules such that each module comprises a plurality of light emitting diodes (LEDs) adapted to emit light. The illumination system further comprises a plurality of lens elements disposed subsequent to the LEDs. Further, a number of the lens elements corresponds to a number of LEDs; such that the plurality of lens elements is adapted to redirect the light emitted by the LEDs on a plurality lenses. The illumination system further comprises a plurality of imagers disposed subsequent to the plurality of lenses, such that each of the imagers forms an image from the light provided by each of the lenses, respectively. Further, the images formed by the plurality of imagers are combined by a device, such as an X-cube, to form a single image that is further provided to a light pipe of a display system.

FIELD OF THE INVENTION

The present invention relates generally to video display and projectionsystems. More specifically, the present invention relates toillumination systems of video display and projection systems.

BACKGROUND OF THE INVENTION

This section is intended to introduce the reader to various aspects ofart, which may be related to various aspects of the present inventionthat are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Typically, video display and projection systems employ an illuminationsystem (for example, a light engine) for generating light ultimatelyused to form an image. Multi-imager systems, such as high temperaturepolysilicon (HTPS) systems or even digital light processor (DLP) systemstypically employ a single illumination system that utilizes aspecialized high pressure mercury arc lamp as an illumination source.The arc lamp is adapted to provide the illumination system with whitelight, which is subsequently split or dispersed using optical devices(e.g., color wheel, filters, etc.) into three primary colors, namely,red green and blue (RGB). Thereafter, the RGB light is combined usingyet additional optical devices for generating a colored image.

The usage of arc lamps as an illumination source in video units hasvarious shortcomings. For example, arc lamps used in the above systemsmay have a relatively short lifetime and may require frequentreplacement. In addition, because the multiple imagers in the abovesystems are dependent on the single lamp as an illumination source, allof the imagers of the system can become simultaneously non-operationalshould the lamp malfunction. Further, replacement of the lamp may becumbersome, requiring major disassembly of the entire display systemand/or some of its elements. By further example, the above mentionedoptical and other devices typically used to disperse and, thereafter,recombine the light may occupy a substantial amount of space within theillumination and projection systems in which they are employed.Accordingly, these optical devices may dictate that the video displayunit in which they are disposed is undesirably large. In addition,mercury contained within some of the arc lamps render those lampsenvironmentally unfriendly.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the invention may become apparent upon reading thefollowing detailed description and upon reference to the drawings inwhich:

FIG. 1 is a block diagram of a video unit in accordance with anexemplary embodiment of the present invention;

FIG. 2 is a block diagram of an illumination system in accordance withan exemplary embodiment of the present invention;

FIG. 3 is block diagram of an illumination system used in conjunctionwith a multi-imager system, in accordance with an exemplary embodimentof the present invention;

FIG. 4 is a perspective view of a lenslet assembly in accordance with anembodiment of the present invention; and

FIG. 5 is a process flow diagram showing a method for illuminating amulti-imaging system, in accordance with an exemplary embodiment of thepresent invention.

DETAILED DESCRIPTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, not all features of an actual implementation are describedin the specification. It should be appreciated that in the developmentof any such actual implementation, as in any engineering or designproject, numerous implementation-specific decisions must be made toachieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

Turning initially to FIG. 1, a block diagram of a video unit inaccordance with one exemplary embodiment of the present invention isillustrated and generally designated by a reference numeral 10. In theillustrated embodiment, the video unit 10 may comprise a Digital LightProcessing (“DLP”) projection television or projector or the like. Inanother embodiment, the video unit 10 may comprise a liquid crystaldisplay (“LCD”) projection television or projector or the like. In stillother embodiments, the video unit 10 may comprise a liquid crystal onsilicon (LCOS) projector, a high temperature poly-silicon (HTPS) oranother suitable form of projection television or display.

The video unit 10 includes a light engine/illumination system 12. Theillumination system 12 is configured to generate white or colored lightthat can be employed by an imaging system 14 to create a video image.The illumination system 12 may be made up of multiple illuminationsystems, for example, such as those used in HTPS systems. As will bediscussed in further detail below, the illumination system 12 includesoptical and electro-optical components adapted to replace arc lampsotherwise used in conventional systems. The illumination system 12includes module(s) having a collection of pulsed light emitting diodes(LEDs) adapted to emit, for example, RGB light at various intensities.As will be further shown below, the illumination system 12 furtherincludes an optical device, referred to herein as a lenslet assembly.The lenslet assembly is a collection of lens elements whose number isequal to the number of the above-mentioned LEDs. The lenslet assembly isadapted to collect and further transmit the RGB light emanating from theLEDs onto an aperture. In this manner, the illumination system 12 isconfigured to efficiently convey the light provided by the illuminationsystem 12 onward to a light pipe of the video unit 10. As those skilledin the art will appreciate, the term light pipe used herein refers tocomponents and optical connections/coupling of the video unit 10disposed subsequent to the illumination system 12. Such components ofthe video unit 10 may include an imaging system, a projection system, ascreen, optical devices couplings and so forth.

Hence, the illumination system 12 utilizes a plurality of LEDs insteadof an arc lamp as an illumination source. In other words, rather thanemploying a lamp for generating white light and components (e.g., colorwheels, dichroic mirrors, polarizes, filters, etc.) for dispersing andseparating the white light, the illumination system 12 efficientlycombines the light produced by the LEDs at the outset to form coloredand white light at various intensities. The video unit 10, therefore,may be made to be smaller in size as compared to those systems employingarc lamps and/or similar devices used for generating white light as anillumination source.

As described above, the illumination system 12 may be configured toproject, shine, or focus colored light at the imaging system 14. Theimaging system 14 may be configured to employ the colored light tocreate images suitable for display on a screen 24. It should beappreciated that the imaging system 14 may be made up of multipleimaging systems, such as those used in HTPS systems having multipleimagers. As illustrated below (FIG. 3), each of the multiple imagersincluded within the imaging system 14 may be individually coupled to anillumination source, similar to those included within the illuminationsystem 12.

The imaging system 14 may be configured to generate one or more pixelpatterns that can be used to calibrate pixel shifting in the video unit10. In one embodiment, the imaging system 14 comprises a DLP imagingsystem that employs one or more DMDs to generate a video image using thecolored light. In another embodiment, the imaging system 14 may employan LCD projection system. It will be appreciated, however, that theabove-described exemplary embodiments are not intended to be exclusive,and that alternate embodiments, any suitable form of imaging system 14may be employed in the video unit 10.

The imaging system 14 illustrated in FIG. 1 may be configured to projectimages into a projection lens assembly 16. The projection lens assembly16 may include one or more lenses and/or mirrors that project the imagecreated by the imaging system 14 onto the screen 24.

FIG. 2 is a block diagram of the illumination system 12 in accordancewith an exemplary embodiment of the present invention. As mentionedabove, the illumination system 12 includes light generating andcollecting components adapted to convey the colored light to imaging andprojection devices of the video unit 10 (FIG. 1). The illuminationsystem 12 includes an LED module 40 adapted to house a plurality of LEDs42. Each of the LEDs 42 may be pulsed at a certain fast rate. Further,each of the LEDs 42 contained within the module 40 may be adapted toemit red, green or blue light. Other embodiments may incorporate LEDs,i.e., LEDs 42, adapted to emit light of various colors, some of whichmay be different from red, green or blue. In addition, the module 40 maybe adapted to house N LEDs. In an exemplary embodiment, the module 40may be adapted to house up to eleven LEDs. In other exemplaryembodiments, the module 40 may include up to five or seven LEDs. Instill other exemplary embodiments, the illumination system 12 may beadapted to include multiple LED modules, such as the modules 40. In suchembodiments, each of the modules 40 may be adapted to house a differentnumber of LEDs. It should be noted that the number of LEDs includedwithin each of the modules 40 may be determined by system design and/oroperation criteria and/or by cost effective goals.

Hence, the module 40 is adapted to house combinations of RGB LEDs. Suchcombinations can be used, for example, to accentuate and/or suppresslight of a specific color. For instance, a suitable combination of LEDscan configure the video unit 10 to produce images having hues that arerelatively greater in red than blue. This may be achieved by includingwithin the module 40 a greater number of LEDs producing red light thanthose LEDs producing blue light. Similarly, the module 40 may be adaptedto house other combinations of LEDs, such as those envisioned to outputlight with enhanced and/or suppressed color(s) of different kinds.

The ability to incorporate and/or change the amount of LEDs within theillumination system 12 is facilitated by a modular design of the module40. That is, each of the LEDs 42 may be independently coupled to themodule 40 such that one or more of the LEDs 42 can be replaced and/orremoved form the module 40 with minimal effort. Further, should one ormore of the LEDs 42 malfunction or otherwise become idle, the video unit10 may continue to project images despite some loss in color and/orbrightness. Hence, unlike systems employing arc lamps whose malfunctionrenders the entire video unit nonfunctional, the present techniqueenables the video unit to continue operating even though one or more ofthe LEDs is non operational. Further, those skilled in the art willappreciate that the average lifetime of an LED is far greater than theaverage lifetime of an arc lamp. This yet provides another advantage ofusing the LEDs 42 as an illumination source rather the mercury lamp usedin conventional systems.

The illumination system 12 further includes a plurality of lightcollimating elements or collimators 44 adapted to efficiently collectthe light produced by the LEDs 42. In an exemplary embodiment, each ofthe collimators 44 may be disposed near or directly adjacent to each ofthe LEDs 42. In other exemplary embodiments, each of the collimators 44may surround each of the LEDs 42 such that the LEDs 42 may be partiallyembedded within the collimators 44. Each of the collimators 44 isadapted to intake a maximal amount of light emanating from the LED towhich the collimator is coupled. In so doing, the collimators 44increase the light gathering ability of the illumination system 12. Thisensures that the majority of the light produced by the LEDs 42 can beefficiently provided to and utilized by subsequent optical components ofthe video unit 10 for generating an image.

The illumination system 12 further includes a lenslet assembly 46. Thelenslet assembly 46 includes a plurality of optical components, referredto herein as lenslets or lens elements. Hence, the lenslet assembly 46is a collection of individual lenslets or lens elements. The number oflenslets included in the lenslet assembly 46 corresponds to the numberof LEDs 42 included in the module 40. Each of the lenslets is adapted toreceive light emitted by a respective LED 42 and collimator 44. Further,after receiving the light for the respective LED, each of the lensletsof the assembly 46 is adapted to redirect the light onto a lens 48disposed subsequent to the lenslet assembly 46. As will be further shownbelow, each of the lenslets 46 is geometrically oriented relative to anaxis for optimally receiving and redirecting the light emanating fromeach of the respective LEDs 42 onto the lens 48. In so doing, thelenslets 46 ensure that the lens 48 receives and collects a maximalamount of light emitted by the LEDs 42. Further, once the lens 48receives the redirected light, the lens 48 focuses the light onto anaperture 50. The aperture 50 is adapted to transmit the light into alight pipe comprising additional imaging and projection components, asdiscussed hereinabove in relation to FIG. 1.

The lenslet assembly 46 is adapted to provide a unique intensitydistribution at the aperture 50 for each of the LEDs 42. The intensitydistribution for each of the LEDs 42 at the aperture 50 depends on thelocation of each of the LEDs 42 in module 40 and on the orientation ofthe respective lenslets 46 relative to lens 48. By virtue of includingthe lenslet assembly 46 within the illumination system 12, properintensity levels of the LEDs 42 are obtained at the aperture 50 forprojecting an image. In other words, absent the lenslet assembly 46, thelight emerging from the LEDs 42 cannot be collected efficiently ataperture 50 for projecting a viewable image.

FIG. 3 is a block diagram of an illumination system used in conjunctionwith a multi-imaging system, in accordance with an exemplary embodimentof the present technique. Illumination system 70 includes multiplecomponents similar to those discussed above in relation to theillumination system 12 of FIG. 2. Hence, the illumination system 70 isadapted for display units employing multiple imagers. Such display unitsmay include HTPS systems or large projectors used to project very largeimages, such as those, encountered, for example, in theaters, cinemas orthe like.

As illustrated, the illumination system 70 includes three illuminationmodules 72, 74 and 76, similar to the module 40 (FIG. 2), whosecharacteristics and attributes are incorporated herein by reference.Other exemplary embodiments may incorporate a different number ofillumination modules (e.g., modules 72-76) for accommodating video unitswith a corresponding number of imagers. Further, each of the modules72-76 includes a plurality of LEDs, such as the LEDs 42 discussed inrelation to FIG. 2. It should be appreciated that the modules 72-76 mayeach house a different amount of LEDs. As illustrated by FIG. 3, thetotal number of LEDs housed within each of the modules 72-76 is denotedby M, N and Q, respectively.

In an exemplary embodiment, each of the modules 72-76 includes LEDsadapted to emit light signals of a specific color. For example, themodule 72 may house LEDs (e.g., LEDs 42) adapted to emit only red lightsignals. Similarly, the module 74 can house LEDs 42 that emit only greenlight, and the module 76 may house LEDs adapted to emit only blue light.In other exemplary embodiments, each of the modules 72-76 may house LEDsadapted to emit light signals of various colors some of which are notRGB. In still other embodiments, the modules 72-76 may housecombinations of LEDs, where each LED is adapted to emit light signals ofa different color.

As further illustrated, each of the modules 72-76 are coupled tocollimators 78, 80 and 82, respectively. The collimators 78-82 areadapted to efficiently gather light from each of the LEDs 42 disposedwithin the modules 72-76. The collimators 78-82 are coupled to themodules 72-76 in a manner similar to that discussed above in relation tothe collimator 44 of FIG. 2. Accordingly, the collimators 78-82 haveattributes and characteristics similar to the collimator 44 incorporatedherein by reference. The illumination system 70 further includes threelenslet assemblies 84, 86 and 88 disposed subsequent to the collimators78-82, respectively. Each of the lenslet assemblies 84-88 includes aplurality of lenslets similar to those associates with the lensletassembly 46 of the illumination system 12. A number of lensletsincorporated within the lenslet assemblies 84-88 corresponds to thenumber of LEDs included in the modules 72-76. Further, each of thelenslet assemblies 84-88 are adapted to receive the light signalsemanating from the respective modules 72-76. In so doing, the lensletsof the assemblies 84-88 are further adapted to redirect the light ontolenses 90, 92 and 94, respectively.

The lenses 90-94 are similar to the lens 48 discussed above in relationto the illumination system 12 of FIG. 2. Hence, the lenses 90-94 areadapted to collect and focus the light provided by each of the lensletassemblies 84-88 onto polarization elements 96, 98 and 100. Thepolarization elements 96-100 are adapted to polarize the light signalsemanating from each of the collimators lenses 90-94, respectively. Thatis, each of the polarization elements may distinctly polarize the lightprovided by the LEDs 42. For example, in one embodiment, the polarizingelement 96 may render the light received from the collimator 78 to bes-polarized. Similarly, the polarizing elements 98 and 100 may renderthe light emanating from the collimators 80 and 82, respectively, to bep-polarized. Those skilled in the art will appreciate that thepolarizing elements 96-100 can be employed in a variety of ways so as toprovide different polarization schemes for polarizing the light signalsemitted by the LEDs 42.

The illumination system 70 further includes a plurality of imagers102-106 disposed subsequent to the polarization elements 96-100. Theimagers 102-106 are adapted to image the light provided by each of theLEDs 42 of modules 72-26, respectively. The images formed by the imagers102-106 are, thereafter, provided to an X-cube 108, which combines andprovides those images to a light pipe of the video unit 10.

FIG. 4 is perspective view of an illumination system including a lensletassembly, in accordance with an embodiment of the present technique. Thelenslet assembly depicted in FIG. 4 is similar to those discussed hereinin relation to FIGS. 2 and 3. As illustrated, the lenslet assembly 46 isdisposed subsequent the lens 48. In the illustrated embodiment, thelenslet assembly 46 forms a structure that includes five lenslets 60,corresponding to five LEDs included within the module 40 and or withinthe modules 72-76 (FIGS. 2 and 3, respectively). Other exemplaryembodiments may include lenslet assemblies having a different number oflenslets, for example, such as seven or eleven lenslets, correspondingto a similar number of LEDs. Each of the lenslets 60 may be made up froman optical plastic, such as an acrylic complex or a similar material.Each of the lenslets 60 may be molded into a semi-convex structurehaving a lens-like structure. In the illustrated embodiment, each of thelenslets 60 may have one flat-shaped side facing the module 40 (FIG. 2),and one relatively curved/convex shaped-side facing the lens 48.

As further illustrated by FIG. 4, each of the lenslets 60 is disposedabout an axis 62. While in the illustrated embodiment, the lensletassembly 46 may be disposed symmetrically transverse relative to theaxis 62, other embodiments may include disposing the lenslet assembly 46asymmetrically transverse relative to the axis 62. Further, each of thelenslets 60 may generally have a unique orientation relative to the axis62, the module 40 (LEDs 42) and the lens 48. The unique orientation ofeach of the lenslets 60 relative to the aforementioned componentsensures that each of the lenslets 60 optimally captures the lightemitted by the respective LEDs disposed within the module 40 and/or themodules 72-76. In other words, each of the lenslets 60 is adapted tooptically couple its respective LED 42 to the lens 48.

FIG. 5 is a process flow diagram showing a method for illuminating aprojection system in accordance with an exemplary embodiment of thepresent invention. The method is generally referred to by the referencenumber 180. The method 180 can be applied to the illumination systems 12and 70 described above in relation to FIGS. 2 and 3. The method 180begins at block 182. Process flow then proceeds to block 184, in whichan illumination system of a video unit emits light by a plurality ofmodules, such as modules 72-76, where each module includes a pluralityof LEDs (e.g., LEDs 42). Block 184 may also include an act ofcollimating the emitted light, as may be performed by the collimators78-82. As mentioned above, the collimation increases the amount of lightavailable for projecting an image onto a screen of the video unit.Thereafter, at block 186, the light emitted by each of the modules 72-76is received by a plurality of lenslet assemblies, such as the lensletassembly 84-88, adapted to redirect the light emanating by the LEDstowards lenses, such as lenses 90-94 (FIG. and 3 and 4). It should beappreciated that the act of receiving and redirecting the light, asperformed at block 186, is applied by each lenslet 60 of eachmodule84-88 to each light ray emanating from a respective LED containedwithin the modules 72-76.

From block 186 the method 180 proceeds to block 188, where the lightredirected by the lenslet assemblies is received by a plurality ofimaging systems, such as the imagers 102-106. Each of the imagers formsan image from the light signals provided by each of the aforementionedlenslet assemblies. Thus, for a system having, for example, threelenslet assemblies, three independent images are formed by the imagers.Block 188 may further include the step of focusing the redirected lightby a plurality of lenses before the light is provided to the pluralityof imagers. Next, at block 190, the images formed by the imagers 102-106(FIG. 3) are combined, for example, by an X-cube to form a single imagewhich is, thereafter, projected onto a screen.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and will be described in detail herein. However,it should be understood that the invention is not intended to be limitedto the particular forms disclosed. Rather, the invention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the invention as defined by the following appended claims.

What is claimed is:
 1. An illumination system, comprising: a pluralityof modules comprising a plurality of light emitting diodes (LEDs)adapted to emit light; a plurality of collimators each configured toreceive the light from a respective one of the plurality of modules; aplurality of lenslet assemblies comprising a plurality of lens elements,each of the plurality of lens elements configured to receive the lightfrom a respective one of the LEDs through a respective one of theplurality of collimators, wherein a number of plurality of lens elementscorresponds to a number of the LEDs, and wherein the plurality of lenselements is adapted to redirect the light emitted by the LEDs on aplurality of lenses each configured to receive the light from arespective one of the plurality of lenslet assemblies; and a pluralityof imagers each configured to receive the light from a respective lensof the plurality of lenses, wherein each of the imagers forms an imagefrom the light provided by each of the lens elements, respectively. 2.The illumination system of claim 1, comprising a plurality of polarizingelements disposed between the plurality of lenses and the plurality ofimagers.
 3. The illumination system of claim 1, wherein each of the LEDsis adapted to emit red, green or blue light.
 4. The illumination systemof claim 1, comprising an X-cube adapted to combine the images formed bythe imagers.
 5. The illumination system of claim 1, wherein each of theplurality of lenslet assemblies is disposed symmetrically transverserelative to a line that runs therethrough and through a one of theplurality of lenses configured to receive the light from the respectiveone of the plurality of lenslet assemblies.
 6. The illumination systemof claim 1, wherein each of the plurality of lenslet assemblies isdisposed asymmetrically transverse relative to a line that runstherethrough and through a one of the plurality of lenses configured toreceive the light from the respective one of the plurality of lensletassemblies.
 7. The illumination system of claim 1, wherein the pluralityof lens elements is adapted to increase the efficiency of light providedto a light pipe of a video unit.
 8. A method of operating anillumination system of a video unit, comprising: emitting light from aplurality of modules, wherein each of the modules comprises a pluralityof light emitting diodes (LEDs); collimating the light from the LEDs ina plurality of collimators; redirecting the light by a plurality oflenslet assemblies, wherein each of the plurality of lenslet assembliescomprises a plurality of lens elements whose number is equal to a numberof the LEDs, and wherein each of the plurality of lens elements isconfigures to receive the light from a respective LED through arespective collimator; collecting and focusing the redirected light by aplurality of lenses, wherein each lens of the plurality of lensesconfigured to receive the light from a respective lenslet assembly;forming images from the redirected light provided by each one of thelenslet assemblies; and combining the formed images to form a singleimage adapted to be projected on a screen by the video unit.
 9. Themethod of claim 8, comprising polarizing the light provided by theplurality of lenslet assemblies.
 10. The method of claim 8, comprisingpulsing the light emitted by each of the plurality of LEDs.
 11. Themethod of claim 8, comprising emitting red, green and blue light by theplurality of LEDs.
 12. The method of claim 10, wherein redirectingcomprises receiving light by one of the plurality of lens elements froma respective one of the plurality of LEDs, and transmitting the lightonto a respective lens.
 13. A video unit, comprising: an illuminationsystem, comprising: a plurality of modules comprising a plurality oflight emitting diodes (LEDs) adapted to emit light; a plurality ofcollimators each configured to receive the light from a respective oneof the plurality of modules; a plurality of lenslet assembliescomprising a plurality of lens elements, each of the plurality of lenselements configured to receive the light from a respective one of theLEDs through a respective one of the plurality of collimators, wherein anumber of plurality of lens elements corresponds to a number of theLEDs, and wherein the plurality of lens elements is adapted to redirectthe light emitted by the LEDs on a plurality of lenses each configuredto receive the light from a respective one of the plurality of lensletassemblies; and a plurality of imagers each configured to receive thelight from a respective lens of the plurality of lenses, wherein each ofthe imagers forms an image from the light provided by each of thelenses, respectively; an imaging system adapted to form an image basedon the light received from the illumination system; and a projectionsystem adapted to project the image on a screen of the video unit. 14.The video unit of claim 13, comprising a plurality polarizing elementsdisposed between the plurality of lenses and the plurality of imagers.15. The video unit of claim 13, wherein each of the LEDs is adapted toemit red, green or blue light.
 16. The video unit of claim 13,comprising an X-cube adapted to combine the images formed by theimagers.
 17. The video unit of claim 13, wherein the plurality of lenselements are disposed within a plurality of lenslet assemblies.
 18. Theillumination system of claim 1, wherein each of the plurality ofcollimators surrounds a respective LED such that the respective LED ispartially embedded in the respective collimator.
 19. The illuminationsystem of claim 1, wherein each of the lens elements comprises aflat-shaped side facing the respective module and a convex-shaped sidefacing the respective lens.